Take a look at the Calendar for 2017. January 1st falls on a Sunday, so for the first time in a number of years, there is no "partial week that starts in the previous year and ends in the first part of January. Thus, a January date in the days 1 thru 7 range will have a week of year value of 1 and be odd.

I can't provide a work around to fix this as I don't know how you are using the fact that the first week of the year might be odd or even in your calculations.

Take a look at the Calendar for 2017. January 1st falls on a Sunday, so for the first time in a number of years, there is no "partial week that starts in the previous year and ends in the first part of January. Thus, a January date in the days 1 thru 7 range will have a week of year value of 1 and be odd.

I can't provide a work around to fix this as I don't know how you are using the fact that the first week of the year might be odd or even in your calculations.

Going forward, You can simply record whether the first week is odd or even in a global field or variable each time the file opens or use a relationship to link to a record that records this detail. Then compare whether the current week is odd or even to whether the first week is odd or even in order to show either Week 1 or Week 2....